This invention relates to a device for safely locating a stent or stent graft at a diseased site in order to treat a stenotic and expansive disease such as an aneurysm of an artery and other disease conditions.
An aneurysm which grows due to hardening or inflammation of an artery, when left untreated expands gradually and fatally ruptures creating a disease condition that has no prognosis. Medicine has little effect on this type of disease condition. Therefore, in order to cure an aneurysm, a surgical operation using an artificial blood vessel, e.g. an operation involving removal of cancer tissue and of replacement by the artificial blood vessel has traditionally been performed. However, this type of disease condition is often experienced by old which increases the likelihood of multiple organ failure such as disorders of the brain, heart the kidneys, etc. In addition, the surgical operation is often excessively invasion. Thus, a surgical operation for this disease condition that is limited to safe technique which can avoid the danger of these difficulties is desired. Accordingly, much attention has been paid to the treatment of blood vessels using catheters which is less invasion.
A stent is an artificial tubular structure that is inserted into an internal tubular organ such as a blood vessel for the purpose of supporting it. When an internal tubular organ such as a blood vessel, gallbladder, esophagus, intestines, urethra, etc. suffers stenosis or deformation, stent is inserted into the internal tubular organ to support it so that the stenosis and deformation are prevented. A stent which has been widely applied clinically in order to treat an arterial stenotic disease is a cylinder formed of a wire mesh or spring made of stainless steel or a shape memory alloy (NiTi). The cylinder is formed to be shrinkable or expandable repeatedly in a radial direction. A stent graft is a polyester or Teflon artificial blood vessel in which a stent cylinder formed of mesh or a spring made of stainless or nickel titanium is sewed therein. Stent grafts have effectively been used to treat aneurysms. Such stents and stent grafts are disclosed in JP-A-7-24072, JP-A-7-47134, JP-A-7-500272 (PCT), JP-A-8-299456 (PCT), JP-A-8-502428 (PCT) and JP-A-8-511487 (PCT).
Stents and stent grafts are located in diseased portions of blood vessels through catheters. Specifically, the stent or stent graft is compressed to have a diameter smaller than the inner diameter of a fine catheter and is housed in the catheter. The stent or stent graft is inserted from an incised part of a peripheral artery such as a femoral artery into the diseased portion of the blood vessel. The stent or stent graft is extruded from the catheter and expanded to a prescribed diameter in a radial direction. The stent or stent graft is further located in the diseased portion of the blood vessel, thereby expanding an artery stenotic disease and closing the aneurysm while reconstructing a blood flow. The treatment using the stent or stent graft is acceptably invasive. Therefore, it can reduce the burden imposed on a patient, and can be also applied to aneurysm diseases. Thus, this treatment is effective for patients suffering from arterial stenotic diseases and expansive diseases.
However, conventional stents and stent grafts cannot be contracted again after they have been discharged from a catheter to expand and located in a blood vessel. Therefore, when a disorder of the blood stream and internal organ happen because of erroneous positioning of the stent or stent grafts, they cannot be moved or recovered.
Further, in order to ensure closure of an aneurysm conventional stent grafts must be located over a wider range including not only the aneurysm but also the normal artery on the central and peripheral sides of the aneurysm so that the contact between the stent graft and the internal face of the artery is assured. However, in this case, a problem is created when the stent graft also closes the main artery which branches from the vicinity of the aneurysm to generate organ disorder (hereinafter referred to as xe2x80x9cposition abnormalityxe2x80x9d). For example, in the case of an abdominal aortic aneurysm, when the artery such as a renal artery, inferior mesenteric artery, internal iliac artery, etc. is closed, there can be renal failure or colon ischemia. Likewise, in the case of a thoracic aortic aneurysm, when an intercostal artery is closed, there can be spinal cord ischemia, leading to serious complication of paralysis of a lower half of a patient""s body.
The inventor of the present invention supposed as follows. It is assumed that a stent or stent graft which can recovered from the body can be located temporarily at a diseased portion of a blood vessel before the conventional stent or stent graft is located at the diseased part. In this case, if a dangerous portion where a blood flow disorder may occur when the conventional stent or stent graft is located in the blood vessel and a safe portion where no blood flow disorder exits are taken beforehand as video information, the conventional stent can be located at the safe point of the blood vessel. On the basis of this idea, the inventor of the present invention proposed a temporarily locating type stent or stent graft which can be recovered from the body after it is temporarily located (JP application No 9-151372).
Hereinafter, in the specification, a stent or stent graft which can be located temporarily at a diseased portion of a blood vessel is referred to as a xe2x80x9ctemporarily locating type stent or stent graftxe2x80x9d. On the other hand, the conventional stent or stent graft, which is permanently located at the diseased portion should be referred to as xe2x80x9cpermanently locating type stent or stent graft, but will be referred to as simply xe2x80x9cstent or stent graftxe2x80x9d as they are traditionally called.
In FIG. 12, reference numeral 111 denotes a temporarily locating type stent proposed by the inventor of the present invention. The temporarily locating type stent 111 is composed of a stent body 112 at the front and mast lines 118 at the rear. The stent body 112 has three elastic rings 114 each formed in a ring shape by a metallic wire bent in a zigzag manner. Each elastic ring 114 is made of a material such as stainless steel, titanium, shape memory alloy, etc. Around the elastic ring 114, eight coupling wires 115 are arranged at regular intervals in a circumferential direction of the ring. These coupling wires 115 are welded or soldered on the elastic rings 114 at their points of intersection of them to form an elastic cylindrical body 114. The elastic cylindrical body 113 is aligned with parallel portions 116 of the coupling wires 115. The mast lines 113 whose tips 119 are connected to the parallel portions 116 in the stent body 112 extend rearward as bundle. The coupling wires 115 and mast wires 11S are made of continuous shape memory alloy. The bundle of the mast wires 113 has a diameter which is slightly smaller than the inner diameter of a catheter 131. The mast wires 11S have a length sufficient to penetrate through the catheter 131 and to be operable outside the body when the stent body 112 is located at a prescribed position in a blood vessel. The stent body 112 and the mast wires 118 are sufficiently rigid to endure extrusion from the catheter 131 by manipulation from outside of the body and to be pulled into the catheter 131. The catheter 131 is equipped, at its outlet with an R-shape so that the stent body 112 can be contracted smoothly and received in the body.
The temporarily locating type stent or stent graft can be used to determine beforehand, as video information, the dangerous part where the blood flow disorder may happen in the diseased portion in e.g. the blood vessel, and a safe port where no blood flow disorder exists. This temporarily locating type stent permits the permanent locating type stent to be located on the safe point of the diseased portion. However, the temporarily locating type stent takes a long time for this use so that a patient is caused pain and burdened, and the procedure is costly.
The present invention intends to solve these problems.
More specifically, the present invention intends to provide a device for locating a stent or stent graft which can locate the stent or stent graft at a diseased portion safely, and reduce pain or burden for a patient and the cost required for the procedure.
In order to attain the above object, the present invention provides a stent or stent graft locating device comprising a number of leading wires, a pushing rod for holding the number of leading wires in its circumferential direction and a sheath for loading the pushing rod therein.
The invention further provides a stent or stent graft locating device in which a pushing rod is composed of an inner tube and an outer tube, a hollow portion of the inner tube is used as a guiding wire channel and another sectional ring-shaped hollow portion between the inner tube and the outer tube is used as a leading wire channel.
The invention further provides a stent or stent graft locating device in which a pushing rod is constructed of a single tube, a hollow portion of the tube is used as a guiding wire channel and a plurality of leading wire channels are arranged in a body of the tube at approximate regular intervals in its circumferential direction.
The invention also provides a stent or stent graft locating device in which a pushing rod has a plurality of leading wires which are derived from the tip of a leading wire channel and scattered at approximate regular intervals in the circumferential direction.
The invention further provides a stent or stent graft locating device in which a pushing rod has a plurality of leading wires which are derived from the tip of a leading wire channel and scattered at approximate regular intervals in the circumferential direction, and the plurality of leading wires cross in the vicinity of the tip of said pushing rod so as to form a coarse mesh.
The invention also provides a stent or stent graft locating device in which a pushing rod has a plurality of auxiliary leading wires which are finer and shorter than the leading wires are derived, among the number of leading wires, from the tip of said leading wire channel.
The invention further provides a stent or stent graft locating device in which a pushing rod has plural lead-in wires which are derived from the tip of the leading wire channel and engaged with the knees at the terminal of the stent at approximate regular intervals by detachable engaging means.
The invention also provides a stent or stent graft locating device having an engaging means which is a hook formed by bending the tip of each of the lead-in wires.
The invention moreover provides a stent or stent graft locating device having an engaging means that is a ring screwed into the tip of each of the lead-in wires.
The invention further provides a stent or stent graft locating device having leading wires that are metallic wires of stainless steel, titanium nickel or nickel.
The invention further provides a stent or stent graft locating device having auxiliary leading wires that are metallic wires or stainless steel, titanium nickel or nickel.
The invention moreover provides a stent or stent graft locating device having lead-in wires that are metallic wires of stainless steel, titanium nickel or nickel.
The invention also provides a stent or stent graft locating device in which the stent or stent graft is encircled by a number of leading wires and housed in a sheath.
The invention also provides a stent or stent graft locating device in which the tip of each of a number of leading wires is seamed with an elastic ring-shaped portion of a stent or stent graft by a joining thread.